The present invention relates to a resource management method and apparatus for an information processing system of multitasking facility, and more specifically to a resource reclaiming method and apparatus, upon shortage of resources.
In recent years, the resource management has become more important as the size and the number of processes in a computer system increases.
Conventionally, for example, if a process requests a certain size of the main memory and the amount of free main memory is less than the required size, the process receives a result of memory allocation failure or the process is in wait state until it becomes possible to allocate that amount of memory. Particularly, if the amount of free main memory is insufficient at a process creation, the process would be terminated.
Likewise, if a process requests a certain size of the file area on the disk and the amount of the file area is less than the required size, the process receives a result of file area allocation failure or the process is in wait state until it becomes possible to allocate that amount of file area.
Thus, the problems in the prior art may be summarized as follows.
For main memory resource management, if a process requests an allocation of the main memory and the amount of free main memory is less than the required size, the process receives a result of memory allocation failure or the process is in wait state until it becomes possible to allocate that amount of memory. Therefore, it is often the case that the memory allocation request of a higher prioritized process is blocked for a long time because a lower prioritized process occupies an excess portion of the main memory. Main memory space reclaiming methods used in a conventional computer system do not manage to cope with the case sufficiently.
For disk space resource management, if a process requests an allocation of the file area on the disk and the amount of the free area is smaller than the required size, the process receives a result of file area allocation failure or the process is in wait state until it becomes possible to allocate that amount. Therefore, it is often the case that the file allocation request of a higher prioritized process is blocked for a long time or terminated because of the disk volume shortage. Disk space reclaiming methods used in a conventional computer system do not manage to cope with the case sufficiently.